An inkjet printing system typically includes one or more printheads and their corresponding ink supplies. Each printhead includes an ink inlet that is connected to its ink supply and an array of drop ejectors with each ejector including an ink chamber, an ejecting actuator and an orifice through which droplets of ink are ejected. The ejecting actuator may be one of various types, including a heater that vaporizes some of the ink in the chamber in order to propel a droplet out of the orifice, or a piezoelectric device which changes the wall geometry of the chamber in order to generate a pressure wave that ejects a droplet. The droplets are typically directed toward paper or other recording medium in order to produce an image according to image data that is converted into electronic firing pulses for the drop ejectors as relative motion between the print medium and the printhead is established.
Motion of the print medium relative to the printhead can consist of keeping the printhead stationary and advancing the print medium past the printhead while the drops are ejected. This architecture is appropriate if the nozzle array on the printhead can address the entire region of interest across the width of the print medium. Such printheads are often referred to as pagewidth printheads.
Manufacturing yield of printhead die decreases for larger die sizes, and in many applications it is not economically feasible to fabricate a pagewidth printhead using a single printhead die that spans the width of the print medium, especially when the width of the print medium is larger than four inches. At the same time, the cost of assembly of the plurality of printhead die makes it economically unfeasible to fabricate a pagewidth printhead if the individual printhead die are too small. In order to provide high quality printing, a printhead die suitable for use as a subunit of a pagewidth printhead may have a nozzle density of 1200 nozzles per inch, and have several hundred to more than one thousand drop ejectors on a single die. In order to control the firing of so many drop ejectors on a printhead die, it is preferable to integrate driving transistors and logic circuitry onto the printhead die.
As such, there is a need for a buttable printhead module having driving electronics and logic integrated so that a sufficiently large numbers of drop ejectors can be incorporated on a single module, where sufficient room is available at the butting edge so that drop ejectors and associated electronics are not damaged during separation of the module from the wafer. What is also needed is an alignment feature at the butting edge of the module to accomplish alignment of the modules in both directions in the plane of the modules.